Technical Field of the Invention
The present invention relates to processes, apparatuses and systems for continuously cycling supercritical CO2 and/or other compressed gases through a solid matrix for extracting constituents from that matrix. The described processes, apparatuses and systems incorporate a method for using single gases or combinations of gases of widely varying vapor pressures in ways that maximize extraction efficiency and allow for complete recovery of working gases
Description of the Related Art
Supercritical CO2, hydrocarbons like butane and propane, and refrigerant gases like R134a are used in the natural products industry for extracting constituents, particularly oils, from botanicals, such as those included in the cannabis genus. Each gas has its advantages and disadvantages. For example, extractions utilizing CO2 gas can yield pure extracts with virtually no solvent traces. CO2 also has the characteristic that its solvent properties can be finely adjusted with differences in pressure and temperature. Hydrocarbons such as propane and butane have the advantage of being extremely effective solvents resulting in the ability to complete extraction processes quickly. One downside of using propane or butane as a solvent is their extreme flammability. Because of their high price and flammability recovering all of a hydrocarbon extractor at the end of an extraction process is an important and valuable feature.
In certain cases involving extraction of constituents from certain natural products, combinations of CO2, hydrocarbon and refrigerant gases will overcome certain disadvantages and enhance certain advantages of the extraction process. Until now, there has been a need for an extraction process or system available to the natural products industry which utilizes the gases listed above in an efficient manner. Older extraction systems using gas booster technology were able to conduct CO2 extractions or an extraction using one of the listed lower pressure gases; however such systems could not carry out an extraction using a combination of CO2 and one of the lower pressure gases. This shortcoming of prior gas extraction systems was due in part to the inability of the gas booster technology to accurately combine and pump gas vapors of widely varying vapor pressures due to the propensity of liquefied, pressurized gases to give off their vapor at different rates, determined by their inherent vapor pressures or boiling points.
Furthermore, when utilized in the supercritical extraction of constituents from natural products, gas boosters are inherently slow and prone to requiring high levels of maintenance.